Composition for foundry molds



' Patented July 11, 1933 i JEAN nmrsrn mnumn, or mansmnnn, Eamon v CODOSITION FOR FOUNDRY HOLDS No Drawing. Original application filed April 4, 1930, Serial No. 441,709, and in France and Great Britain November 9, 1929. Divided and this application filed March 10, 1933. Serial No. 660,333.

The present invention is for a composition for foundry molds. This application is a division and continuation of my application Ser. No. 441,709 of Aprilth, 1930, w iich also refers to my application Ser. No. 394,387 filed Se tember21st, 1929.

ne object of the present invention is a composition comprising a subhydrated mix- I ture of a hydraulic binder with artificial sands of any composition having the property of becoming set when mixed with the hydraulic binder and having also the refractory property. ecessary for resisting the cast molten metal.

Another object of the present invention is a composition comprising a subhydrated ma- Y terial obtained by crushing the old molds made by the'processes described in my aforesaid applications Ser. No. 394,387. and

Y 441,709. The mixtures whereof those molds are made'can be re-used to great advantage in the making of other molds becausez' (1) The binding agent forms a body much less resistant than if suflicient water had 25 been used to cause the whole of the binding agent to set, and hence the body is readily reduced by crushing to the fineness of sand; and (2) the binding agent, remaining subhydrated, has still an ailinity for water and the mixture therefore is capable of absorbing water and of partly setting, while still maintaining such a state of dryness that there is no need to stove dry the mold. In thus re-using the material whereof molds have been made according'to the in .vention of my said prior applications, it is advantageous to use an additional quantity of binderalthough it is possible to-make a mold by the addition only of a proper quantit of water.

here are also to be considered as artificial sands for the pur ose of this invention, the materials obtame by crushing the materials as coal, cokes, lignite, talc, baryta, asbestos, etc. all substances sometimes useful for obtaining contact surfaces with the molten metal. It results from this, that the inven-.

tion may be extended to molds having special layers intended for surface contact with the poured metal, for instance by thin layers.

This action of the surface is intended for 1 example to produce-on the castings a peculiar surface aspect or a determined quality of the castings over a certain thickness.

In particular in casting ironobjects the layer directl in contact with the metal may be compose of a mixture of sands richin carbon such as coke with cement, so as to offer to the molten metal a surface not only refrac- 5 tory but also resistant to decomposition, or of W a composition different from that obtained by silicious or aluminous sands ordinarily used. The molds so obtained allow of realizf ing castings having a surface without scorifications and easy to free from sand.

The surfaces thus prepared need not generally be given a coat of paint,- which renders the manufacture of molds very simple. In this, case as it is not necessary to apply a coat of paint the layer formin the contact surface may be less subhydrate than the composition constituting the mold provided that the latter is sufiiciently subhydrated.

' The surface layers of the mold should contain such a quantity of binding agent and materials having such properties as will give i in each case the special results desired. For example, the addition of carbon, such as coke, results in iron castings having non-scorified surfaces; theaddition of coal non-freed from gas results in obtaining crackled surfaces with an ornamental aspectgthe addition of talc baryta, asbestos or magnesia gives very smooth surfaces.

In particular, where a protection layer is used the sand constituting the backing mass of the molds may be made of a natural or artificial sand of any kind. Even a sand of- 1 coarse grains may be used. the effect being to increase the porosity of the mould.

What I claim' is:

1. A composition for the manufacture of foundry molds consisting in a subhydrated ag'glomerate of sand of any species and of a hydraulic binder;

2. A composition for the manufacture of foundry molds comprising crushed molds made of a subhydrated agglomerate of sand and h draulic binder.

3. composition for the manufacture of J CROSS REFERENCE foundry molds consisting in a subhydrated mixture of fresh hydraulic binder and of crushed molds made of a subhydrated agglomerate of sand and hydraulic binder.

4. A mold for foundries consistin in a mixture of sand of an species, set by raulic binder and non-set by raulic binder, said ma- 1 terials being evenly distributed throughout i the mass composin said mold.

I 5. A mold for oundries consisting in a l mixture of an artificial sand having the ropi erties of becoming set when mixed wit hydraulic binder and of resisting cast molten metal, of set hydraulic binder and of non-set hydraulic binder, said materials being evenly distributed throughout the mass composing said mold. 6. A mold for foundries consisting in a lzo mixture of crushed molds made of a subhy- 7. A mold for foundries in which the external arts of the walls thereof are constitlited y an agglomerate of sand of any species and of a hydraulic binder and in which the internal parts of the walls of the mold are constituted by a less subhydrated agglomerate of a sand of any species and of a h draulic binder.

n testimony whereof I have signed this specification.

v JEAN BAPTISTE DURAND.

raj

iao 

